Metal elements for this use are well known in the art, such elements commonly being elongate and of inverted substantially U-shaped cross-section. The metal elements provide a curved portion positioned above the concrete tie and in which a lug of the clip is received, and two substantially parallel vertical sides terminating in downwardly extending anchoring lugs.
The anchoring lugs are embedded in the concrete tie during the pouring thereof to secure the metal element relative thereto, with the sides of the metal element positioned for engagement with a rail in substantially parallel relationship therewith. One of the vertical sides provides an abutment for the foot of the rail, the curved portion providing an anchor positioned above the tie, and which is for the reception of the securing clip.
Commonly, the curved portion includes a convex portion within which the lug of the clip is received, and an adjacent concave portion which provides a seating for another lug of the clip, the clip being of substantially circular cross-section throughout its length.
During the pouring of the concrete tie, it is necessary that concrete be prevented from entering the interior of the curved portion of the metal portion of the metal element, as this would prevent subsequent insertion of the lug of the clip. To prevent concrete from entering the curved portion, it is usual to provide a closure for the curved portion, comprised of moldings of plastics material. These are retained in the metal element by means of notches provided in the anchoring lugs, or, the closures are joined to each other by an interfitting stud and socket arrangement.
This arrnagement has several drawbacks, among which are the requirement to assemble the closure onto the metal element at the work site, and, the possiblity of damage to the relatively fragile end closures in the handling of the relatively heavy metal element, and, the possibility of displacement during the pouring of the concrete. Also, the closures are somewhat difficult to position accurately, and are relatively easily damaged during the pouring of the concrete. Futher, the respective parts are supplied by separate manufacturers, this increasing warehousing and handling costs, and, the overall cost of the on site assembly.